Polycarbosilane adhesion promoters for low dielectric constant polymeric materials

ABSTRACT

The adhesion of low k poly(arylene ether) dielectric coating compositions is effectively enhanced by a polycarbosilane promoter additive or primer. A coating composition is prepared by (a) providing a poly(arylene ether) composition; and (b) adding to said composition a small effective adhesion promoting amount of certain polycarbosilanes. The adhesion enhanced coating compositions are cured by heat treatment at temperatures in excess of 50° C. to form a polycarbosilane-modified poly(arylene ether) polymer composition having a low k dielectric constant for use in semiconductor devices.

This application is a divisional of allowed application Ser. No.09/471,299, now allowed, filed Dec. 23, 1999.

BACKGROUND OF THE INVENTION

a) Field of the Invention

The present invention relates to low dielectric constant (low k) polymercompositions and more particularly to the use of polycarbosilanematerials to enhance the adhesion of low k polymer coatings to adjacentsubstrates.

b) Related Art

In the prior art fabrication of semiconductor integrated circuitdevices, fine patterns of circuitry in the form of semiconductorregions, electrodes, wiring and other components are fabricated onto asemiconductor substrate by using conventional processing, such as etchand chemical vapor deposition (CVD) processes, among others. Afterformation of a wire pattern on the substrate layer, an interlinedielectric material deposition process ensues to both fill in the spacesbetween the horizontally disposed wiring and overcoat the pattern.Alternatively, a damascene technique can be performed in which adielectric layer is deposited onto a substrate, patterned, and etchedback to create recessed regions in which metal is inlaid to createinterconnect wiring. These deposition steps as well as other multi-layerformation processes, well-known in the art, are provided to form amulti-layered integrated semiconductor device.

As the electronics fabrication industry moves towards more compactcircuitry with finer circuit or line geometry in densely-packed circuitpatterns, the dielectric constant requirements of the insulating layersgrows more demanding for lower values. Under these circumstances, theuse of low k polymer dielectrics that minimize capacitance and reducepower consumption and cross talk, while increasing signal propagationspeed, becomes a necessity. The dielectric materials must possessdielectric constants no higher than 3.0 and should have dielectricconstants as low as possible toward a theoretical limit of 1.0. Thepractical expectation for polymer dielectrics is in the range of 2.2 to3.0. For organic dielectrics, thermal stability is an importantconsideration, as semiconductor processing can involve exposure totemperatures in excess of 400° C. The organic dielectrics must haveglass transition temperatures above 300° C. and as high as possibletowards 450° C., as well as a decomposition temperature in excess of450° C. Preferably, the organic polymers should be easily processed bystandard spin-bake-cure processing techniques. The organic dielectricsshould also be free from moisture and out-gassing problems, in additionto having expected adhesive and gap-filling qualities, and dimensionalstability towards thermal cycling, etching, and chemical mechanicalpolishing.

Various polymers have been proposed and utilized as dielectric materialsfor integrated circuits, such polymers including polyimides, and aryleneether polymers. Polyimide resins generally demonstrate high moistureabsorption due to their polarizing chemical structures, resulting in anincreasing dielectric constant. Organosilicon polymers have also beenidentified as low dielectric constant materials. In particular, siloxanebased resins including hydridosiloxane resins, organohydridosiloxaneresins, and spin-on glass siloxanes and silsesquioxanes are used asdielectric layers. Other classes of organosilicon materials includepolyperhydrido-silazanes and nanoporous dielectric silica coatingsformed from liquid alkoxysilane compositions. Most of these materialsexhibit difficulties in processing due to chemical or mechanicalinstability.

Arylene ether polymers have been found particularly useful as low kdielectric materials in IC applications. Arylene ether polymers havebeen identified as organic dielectric materials and include poly(arylene ether) (PAE), poly (arylene ether ether ketone) (PAEEK), poly(arylene ether ether acetylene) (PAEEA), poly (arylene ether etheracetylene ether ether ketone) (PAEEAEEK), poly (arylene ether etheracetylene ketone) (PAEEAK), and poly (naphthylene ether) (PNE)comprising different polymer designs that include homopolymers, block orrandom copolymers, polymer blends, interpenetrating polymer networks(IPNs), and semi-interpenetrating polymer networks (SIPNs). Otherexamples of organic dielectric materials in current use include thepolymeric material obtained from the phenylethynylated aromatic monomerprovided by Dow Chemical Company under the trademark SILK™ and the poly(arylene ether) provided by Schumacher under the tradename VELOX™.

In commonly assigned U.S. patent applications Ser. No. 08/665,189, filedon Jun. 14, 1996, and Ser. No. 09/197,478, filed on Dec. 12, 1997, thereare disclosed certain poly(arylene ethers) which have low dielectricconstants, high glass transition (Tg) temperatures, good thermalstability to and above the Tg, low moisture absorption rate, and goodstorage modulus retention. However, adhesion of these and the othercited organic polymer insulators to substrate surfaces have been foundin need of enhancement, generally requiring addition (or primerapplication) of known adhesion promoters. These prior art adhesionpromoters have been found generally unacceptable in combination with thedielectric poly(arylene ethers) and other organic dielectrics because:(1) their primer application generally requires a separate coatingprocess step; and (2) their presence may generate unanticipated chemicalside reactions (e.g. generation of volitiles due to materials breakdown)during IC high temperature processing.

It has presently been discovered that certain polycarbosilanes can beused as compatible adhesion promoters for low dielectric constantpolymers, particularly poly(arylene ethers), and can be used as anadditive with these polymers and processed to form modified low kdielectric polymeric coating compositions with enhanced adhesivecharacteristics. More precisely, it has been found that the adhesion ofpoly(arylene ether) dielectric coating compositions is particularlyenhanced by the primer application or compositional addition of anadhesion promoter material comprising at least one polycarbosilane. Theinstant polycarbosilane adhesion promoters can be employed as a surfacedeposition treatment (primer) or as an internal compositional additiveto dielectric polymer compositions. These polycarbosilane promoters canbe prepared, provided or used at reasonable cost; and provide enduringadhesion to a variety of surfaces.

SUMMARY OF THE INVENTION

The present invention provides new and improved adhesion promotingmaterials effective in enhancing the adhesion of low dielectric constantpolymer compositions to various substrates. The new and improvedadhesion promoter composition comprises a polycarbosilane of theformula:

in which:

R₁, R₇, and R₁₀ each independently represents a substituted orunsubstituted alkylene, cycloalkylene, or arylene group;

R₂, R₃, R₄, R₅, R₈ and R₉ each independently represents a hydrogen atomor organic group.

R₆ represents an organosilicon, a silanyl, a siloxyl, or an organogroup; and

x, y, z and w satisfying the conditions of [4≦x+y+z+w≦100,000], and yand z and w can collectively or independently be zero.

In order to improve the adhesion of low dielectric constant polymercoatings to electronic surfaces, substrates such as silicon, silicondioxide, silicon nitride and aluminum are treated with the instantpolycarbosilanes as adhesion promoters in two different forms. Thepolycarbosilane materials can be added to surfaces as primer coatingsfrom a solution containing typically from about 0.05 to 20% by weight ofthe polycarbosilane promoter. Alternatively and preferably, thepolycarbosilane adhesion promoters can be compositionally added to a lowk dielectric polymer in certain concentrations and effect in-situadhesion capability in the cured or dried polymer coating composition.When used as surface primers, the present polycarbosilane adhesionpromoter compounds engender superior bonding capacity to substratesurfaces to which low k polymer coatings are subsequently applied. Inmore preferred embodiments, the polycarbosilane adhesion promotercompounds are added to dielectric polymer compositions and subjected toa thermal or high energy source to generate coatings having superioradhesion characteristics throughout the entire polymer composition so asto ensure affinity to any contacted surface of the polymer coating. Theinstant polycarbosilane additives are compatible with low k dielectricpolymers thereby enabling formation of polycarbosilane-modified low kdielectric polymers which possess enhanced adhesive characteristicscompared with the base polymer, while maintaining the other beneficialphysical and electrical properties.

While poly(arylene ether) and the other dielectric organic coatingmaterials have suitable low k dielectric constants and the thermalstability and high mechanical strength characteristics needed forcoating presently miniaturized patterned wiring of semiconductor wafers,these prior art materials have. less resistance to delamination than isdesirable. It has been found that combining poly(arylene ethers) withsmall, effective amounts of the present polycarbosilane adhesionpromoters, spin coating a surface with same, and subjecting theresulting film to a thermal or high energy curing process results in apolycarbosilane-modified poly(arylene ether) polymer film compositionhaving improved adhesion characteristics over those exhibited by thebase poly(arylene ether) base polymer. These films possess a lowdielectric constant, high thermal stability, high mechanical strength,and excellent adhesion to electronic substrate surfaces includingsilicon, silicon nitride, titanium nitride, silicon dioxide, aluminumand tantalum. Because the polycarbosilane is molecularly dispersed,these films demonstrate excellent adhesion to all affixed surfacesincluding underlying substrates and overlayed capping or masking layers,such as SiO₂ and Si₃N₄ capping layers. The use of thesepolycarbosilane-modified polymer films eliminates the need for anadditional process step in the form of at least one primer coatingapplication to achieve adhesion of the film to a substrate and/oroverlaid surface.

In accordance with the invention, new and improved poly(arylene ether)coating compositions exhibiting superior adhesion to electronicsubstrate surfaces are provided, said poly (arylene ether) compositionscomprising:

(a) a poly(arylene ether) having the repeating units of the formula:

[—O—Y₁—O—Ar₁—]_(n)—[—O—Y₂—O—Ar₂—]_(m)  (FORMULA II)

wherein n=0 to 1; and m=1−n; and wherein Y₁, Y₂, Ar₁ and Ar₂ are each adivalent arylene radical, Y₁ and Y₂ being selected from a second groupof divalent arylene radicals; and

(b) a small, effective amount of an adhesion promoter comprised of atleast one polycarbosilane of Formula (I):

In another aspect of the invention there is provided a methodfor.forming electrically insulating films of the instantpolycarbosilane/poly(arylene ether) compositions. This process includesapplying a coating of the instant polycarbosilane/poly(arylene ether)adhesion promoting compositions to an electronic substrate surface andsubjecting the coating to heat or other high energy to cure the coatingthereby forming a thermally stable, adhesive, low dielectric constant (kless than 3.0) polyearbosilane-modified poly(arylene ether) film. Thisfilm generating process can employ any form of energy such as thermal(heat) or other high energy such as electron beam (e-beam), U.V. light,and any other functional forms of high energy. These energy sources areapplied to the instant polycarbosilane/poly(arylene ether) compositionto convert the mixture to low k polycarbosilane-modified poly(aryleneether) film compositions of the present invention. The most expeditiousprocess is the application of thermal energy (heat) to the instantcompositions in increasing temperature thermal plateaus of from about50° C. to about 450° C. The nature of the subjectpolycarbosilane/poly(arylene ether) compositions enables use of generalwet coating and heating processes in the formation of a very lowdielectric constant insulation structures without employing exoticproduction techniques.

The present invention is also directed to a multilayer electroniccircuit article comprising: (i) a silicon, glass or ceramic substrate,(ii) a plurality of layers or regions of an insulating material on asurface of the substrate, and (iii) at least one layer or region of aconductive material selected from the group consisting of metals andsemiconductor materials, interposed between adjacent layers of theinsulating material or within a layer of the insulating material, theinsulating material comprising the low k dielectricpolycarbosilane-modified/poly (arylene ether) coatings of the presentinvention.

When the polycarbosilane/poly(arylene ether) compositions of the instantinvention are subjected to an energizing source such as thermal energy,a polycarbosilane-modified poly(arylene ether) low k dielectric filmcomposition is formed. These low k dielectric composition film coatingshave the unique feature of good adhesion to a variety of commonsemiconductor surfaces without the need for any other prior art adhesionenhancing materials, the addition of which would require undesirableadditional process steps and carry the risk of decomposition resultingin outgassing of these materials in hostile semiconductor processingenvironments. The present polycarbosilane-modified poly (arylene ether)coatings have sufficient glass transition temperature values (Tg) above350° C. so as to form heat resistant, low dielectric constant (low k)semiconductor films which withstand harsh high temperature environmentsin current processing methodology of semiconductor devices.

In addition, the instant dielectric coatings possess good gap fillingqualities for integrated circuits in semiconductor articles andtherefore completely fill spaces between conductive lines of 0.25microns (μm) or less. The low k polycarbosilane-modified poly(aryleneether) coatings of the present invention also possess sufficient thermalstability so as not to evidence any out-gassing during ongoingsemiconductor processing, low moisture absorption to retain filmresistivity, and stability to a variety of common etching and othersemiconductor fabrication processes. As in the case of ordinary organicdielectric materials, the present low k polycarbosilane-modifiedpoly(arylene ether) compositions dielectric coatings can be easilyapplied in high yield to substrates using standard spin-bake-cureprocessing techniques, thus insuring their cost effectiveness. Finally,the polycarbosilane-modified poly(arylene ether) dielectric coatingsdeveloped and disclosed herein are applicable for use in other microelectronic devices in addition to ICs, for example, printed circuitboards (PCBs), multi-chip modules (MCMs) and the like.

The subject invention is based on the finding that certainpolycarbosilanes are excellent adhesion promoters and are compatiblewith poly(arylene ether) compositions. These polycarbosilanes can becompositionally added to the poly(arylene ethers) in small and yeteffective amounts to form the adhesive polycarbosilane-modified poly(arylene ether) semiconductor film coatings of the present invention.The polycarbosilane adhesion promoting compounds are added in small,effective amounts of up to 20% based on the weight of the poly(aryleneether) base polymer composition, and amounts up to about 5.0% by weightof the base polymer are generally preferred. Operable ranges ofpolycarbosilane are from about 0.5 to 20% while preferred ranges arefrom about 0.5 to 5% based on the weight of the poly(arylene ether) basepolymer.

Preferred adhesion promoting polycarbosilane compounds of the inventionare polycarbosilanes in which the R₂ group of Formula I is a hydrogenatom or an and R₁ is methylene and the appendent radicals w, y, and zare zero. Other preferred adhesion promoting polycarbosilane compoundsof the invention are polycarbosilanes of Formula I in which R₂ and R₈are hydrogen, R₁ and R₁₀ are methylene, and R₉ is an alkenyl, andappendent radicals y and z are zero. Examples of preferredpolycarbosilane compounds include poly-dihydridocarbosilane,polyallylhydridocarbosilane, and random copolymers ofpolydihydridocarbosilane and polyallylhydridocarbosilane. The instantpolycarbosilane adhesion promotor compounds can be prepared from wellknown prior art processes or provided by manufacturers ofpolycarbosilane compositions.

Specific embodiments of the new and improvedpolycarbosilane/poly(arylene ether) coating compositions exhibitingsuperior adhesion to electronic surfaces within the scope of the presentinvention are provided by those compositions comprising:

a) 100 parts by weight of a polymer compositition selected from thegroup of poly(arylene ether) homopolymers, block or random copolymers,and polymer blends consisting essentially of: (i) a copolymer of (a)fluorene bisphenol, (b) bis (4-fluoro-phenyl) ethyne and (c)4,4′-difluorobenzophenone in a 2:1:1 monomer ratio; (ii) a homopolymerof (a) fluorene bisphenol, and (b) 4-fluoro-3′-(fluorobenzoyl) tolane ina 1:1 monomer ratio; (iii) a homopolymer of (a) fluorene bisphenol, and(b) bis (4-fluorophenyl) ethyne in a 1:1 monomer ratio: and (iv) ahomopolymer of (a) fluorene bisphenol and (b) 4,4′-difluorobenzophenonein a 1:1 monomer ratio; and

b) from about 0.5 to 20 parts by weight of an adhesion promotercomposition comprising at least one polycarbosilane of the formula:

in which:

R₁ independently represents a substituted or unsubstituted alkylene,cycloalkylene, or arylene group;

R₂ is a hydrogen atom or an organic group; and

x is an average number from about 10 to 15,000.

The new and improved polycarbosilane adhesion promoters and the adhesionenhanced polycarbosilane/poly(arylene ether) coating compositions areefficient and inexpensive to produce and use than prior art materialsand exhibit very satisfactory adhesion to the surfaces of electronicdevices.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more clearly understood from thedescription as set forth below with reference to the accompanyingdrawings wherein:

FIG. 1 is a cross-sectional view of one semiconductor device accordingto the present invention having a planarized dielectric film layercoating for a metallized interconnect structure.

FIG. 2 depicts a damascene structure in the form of a cross section ofthe instant low k dielectric film insulating layer having a recessedregion overlaid with a barrier layer and filled with a metal such ascopper.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to the polycarbosilane adhesionpromoter compositions of Formula I. In another embodiment of theinvention, there is provided a composition comprising:

(a) a poly(arylene ether); and

(b) small, effective amounts by weight of an adhesion promoter comprisedof at least one polycarbosilane of the general formula:

in which:

R₁, R₇, and R₁₀ each independently represents a substituted orunsubstituted alkylene, cycloalkylene, or arylene group;

R₂, R₃, R₄, R5, R₈ and R₉ each independently represents a hydrogen atomor organic group.

R6 represents an organosilicon, a silanyl, a siloxyl, or an organogroup; and

x, y, z and w satisfying the conditions of [4≦x+y+z+w≦100,000], and yand z and w can collectively or independently be zero.

The poly(arylene ethers) of the subject invention have the repeatingunits of the formula:

[—O—Y₁—O—Ar₁—]_(n)—[—O—Y₂—O—Ar₂—]_(m)  (FORMULA II)

wherein n=0 to 1; and m=1−n; and wherein Y₁, Y₂, Ar₁ and Ar₂ are each adivalent arylene radical; Y₁ and Y₂ are each selected from a first groupof divalent arylene radicals; Ar₁ is selected from a second group ofdivalent radicals and Ar₂ is selected from a third group of divalentradicals; the first group of divalent arylene radicals consisting of:

and mixtures thereof; the second group of divalent arylene radicalsconsisting of:

and mixtures thereof; the third group of divalent arylene radicalsconsisting of:

and mixtures thereof. In some embodiments of the present invention Y₁and Y₂ can both be derived from fluorene bisphenol, and n=0.1 to 1. Thepreparation of these poly (arylene ethers) is outlined in the commonlyassigned patent applications cited above, each incorporated herein byreference. These compositions are commercially manufactured anddistributed as FLARE™ poly (arylene ethers) by the instant assignee,AlliedSignal, Inc.

The subject polycarbosilane/adhesion promoting poly (arylene ether)coating compositions are applied to electronic surface substrates. Thecoated substrate is then heat treated and cured at temperatures of from50° C. to about 450° C. to convert the poly(aryleneether)/polycarbosilane mixture to a polycarbosilane-modified poly(arylene ether) polymer composition coating having a low dielectricconstant.

In addition to finding application with the poly (arylene ether)polymers of Formula II above, the polycarbosilane compositions disclosedherein are appropriately used as promoters with many other organicdielectric polymers including poly (arylene ether) (PAE), poly (aryleneether ether ketone) (PAEEK), poly (arylene ether ether acetylene)(PAEEA), poly (arylene ether ether acetylene ether ether ketone)(PAEEAEEK), poly (arylene ether ether acetylene ketone) PAEEAK) andtheir block or random copolymers and blends. Mixtures of one or more ofthe polycarbosilanes of Formula I may be employed in this invention.Alternatively, a promoter mixture including one or more of the instantpolycarbosilanes and another known promoter compound or composition maybe used.

The present invention is a simple, practical and versatile approach toimprove interfacial adhesion between high glass transition temperature(Tg) fluorinated and nonfluorinated poly (arylene ethers) and electronicsurfaces. The invention focuses on the use of a versatilepolycarbosilane polymer adhesion promoter compounds or compositions toaddress the requirement that organic thin films possess high adhesivestrengths to different substrates, in particular silicate and siliconnitride surfaces while at the same time maintaining the high temperaturestability, high mechanical strength and high Tg of the organic polymerfilm.

The invention is further directed to adding certain amounts of adhesionpromoting polycarbosilanes represented by Formula (I) to poly (aryleneethers) represented by Formula (II), coating the mixture onto anelectronic substrate, and heating the coated substrate from about 50° C.to elevated temperatures up to 450° C. under atmospheric or inertblanket environments to convert the polymer mixture to apolycarbosilane-modified poly (arylene ether) polymer film having a lowdielectric constant equal to or less than 3.

It is to be again appreciated that the improved adhesion characteristicsachieved molecularly by the instant polycarbosilane modifiedpoly(arylene ether) compositions renders the adhesion enhanced filmsadherent to any contacted surface. Accordingly, the instant low kpolycarbosilane modified films can be adherent interlayers, effectivelyaffixing to a substrate and an overlayer, as demonstrated in FIG. 2where the polycarbosilane modified poly(arylene ether) sandwich layer isaffixed to both the silicon substrate 32 and the illustrated silicondioxide hardmask overlaid layer 36. This is to be contrasted withconventional primer promoter compositions which additionally requireseparate coating application steps to any surface requiring adhesionenhancement.

The small, effective amounts of polycarbosilane adhesion promoter addedto the base poly(arylene ether) are important to the charateristics ofthe instant polycarbosilane-modified poly(arylene ether) polymercomposition of the instant invention. The quantity of polycarbosilanerange from about 0.5 to 20% by weight of the poly(arylene ether) basecomposition with preferred amounts of polycarbosilane adhesion promoterranging from about 0.5 wt % to about 5 wt. % measured by the weight ofthe poly(arylene ether) base polymer.

In yet another specific embodiment there is provided a process for thepreparation of a organosilicon-modified poly(arylene ether) film coatedelectronic substrate comprising the steps of: (a) providing a solventsolution of a poly (arylene ether) of Formula (II) and an adhesionpromoting polycarbosilane of the above mentioned general formula (I) inan amount of from 0.7 to 5% based on the poly(arylene ether) basepolymer composition; (b) spin coating the poly (aryleneether)/polycarbosilane solution onto an electronic substrate; and (c)heating the coated substrate at gradually increasing temperatures offrom 50° C. to about 450° C., thereby converting the coating to apolycarbosilane-modified poly(arylene ether) polymer low k dielectricfilm composition.

The present invention is particularly advantageously suited for thepoly(arylene ethers) of Formula (II). These and other poly (aryleneethers) disclosed in U.S. patent applications Ser. No. 08/665,189, filedon Jun. 14, 1996, and Ser. No. 08/990,157, filed on Dec. 12, 1997(commonly assigned to AlliedSignal, Inc.) are especially useful withinthe purview of the present invention. And as already indicated, thepolycarbosilane compositions herein presented are useful with a varietyof other organic polymer dielectric materials. These include organicdielectric polymers, such as the nonfluorinated polymeric materialobtained from the phenylethynylated-aromatic monomers and oligomersprovided by the Dow Chemical Company under the trademark SILK™ and thepoly(arylene ether) polymers provided by Schumacher under the trademarkVELOX™, and the fluorinated polymeric materials, such as fluorinatedpolyimides (DuPont Chemical Co.) and Speed Film™, a fluorinated polymersold by W. L. Gore Company.

In the subject adhesion promoting polycarbosilanes of Formula (I), R₁,R₇, and R₁₀, represent substituted or unsubstituted alkylene,cycloalkylene or arylene groups. The R₂, R₃, R₄, R₅, R₈, and R₉ ofFormula (I) each independently represents a hydrogen atom or an organogroup in the form of a substituted or unsubstituted alkyl, alkenyl,alkynyl, or aryl group. The alkyl, alkenyl, and alkynyl groups generallycan contain up to 18 carbon atoms but generally contain from about 1 to10 carbon atoms. Preferred polycarbosilanes of the present inventioninclude dihydrido polycarbosilanes in which the R₂ group is a hydrogenatom and there are no appendent radicals in the polycarbosilane chain;that is, y, z and w are all zero. Another preferred group ofpolycarbosilanes are those in which the R₂, R₃, R₄, R₅, R₈, and R₉groups of Formula (I) are substituted or unsubstituted alkenyl groupshaving from 2 to 10 carbon atoms. The alkenyl group may be ethenyl,propenyl, allyl, butenyl or any other unsaturated organic backboneradical having up to 10 carbon atoms. The alkenyl group may be dienyl innature and includes unsaturated alkenyl radicals appended or substitutedon an otherwise alkyl or unsaturated organic polymer backbone. Examplesof these preferred polycarbosilanes include dihydrido or alkenylsubstituted polycarbosilanes such as polydihydridocarbosilane,polyallylhydrididocarbosilane and random copolymers ofpolydihydridocarbosilane and polyallylhydridocarbosilane.

As can be observed in Formula (I), the adhesion promotingpolycarbosilanes utilized in the subject invention may contain oxidizedradicals in the form of siloxyl groups when z>0. Accordingly, R₆represents an organosilicon, a silanyl, a siloxyl, or an organo groupwhen z>0. It is to be appreciated that the the oxidized versions of thepolycarbosilanes of Formula (II) (z>0) operate very effectively in, andare well within the purview of the present invention. As is equallyapparent, z can be zero independently of x, y, and w the only conditionsbeing that the radicals x, y, z and w of the Formula I polycarbosilanesmust satisfy the conditions of [4<x+y+z+w<100,000], and y and z cancollectively or independently be zero.

The polycarbosilane adhesion promoters or poly (arylene ether) materialsused herein can be produced from starting materials which are presentlycommercially available from many manufacturers. They may be produced byusing conventional polymerizable processes or the proprietarypreparations cited above with respect to the poly (arylene ethers). Asan example of synthesis of the polycarbosilanes, the starting materialscan be produced from common organo silane compounds or from polysilaneas a starting material by heating an admixture of polysilane withpolyborosiloxane in an inert atmosphere to thereby produce thecorresponding polymer or by heating an admixture of polysilane with alow molecular weight carbosilane in an inert atmosphere to therebyproduce the corresponding polymer or by heating an admixture ofpolysilane with a low molecular carbosilane in an inert atmosphere andin the presence of a catalyst such as polyborodiphenylsiloxane tothereby produce the corresponding polymer. Polycarbosilanes can also besynthesized by Grignard Reaction reported in U.S. Pat. No. 5,153,295hereby incorporated by reference. The poly (arylene ether) polymericmaterials can be prepared in accordance with processes outlined and/ordisclosed in the patent applications cited above and hereby incorporatedby reference.

Additives can be used to enhance or impart particular target propertiesto the instant poly (arylene ether)/polycarbosilane adhesion promotercompositions, as is conventionally known in the polymer art, includingadditional adhesion promoters, stabilizers, flame retardants, pigments,plasticizers, surfactants, and the like. Compatible or non-compatiblepolymers can be blended in to engender a desired property in addition tothe adhesion enhancement provided by the present polycarbosilaneadhesion promoters.

Film or coatings of the instant poly(arylene ether)/polycarbosilanepolymer mixture of Formulas I and II can be formed by solutiontechniques such as spraying, spin coating, or casting, with spin coatingbeing preferred. Suitable solvents for use in such solutions of theadhesion promoted poly (arylene ether) compositions of the presentinvention include aprotic solvents, for example, cyclic ketones such ascyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone (aspractical examples); cyclic amides such as N-alkylpyrrolidinone whereinthe alkyl has from about 1 to 4 carbon atoms (as practical examples) andN-cyclohexylpyrrolidinone and mixtures thereof. A wide variety of otherorganic solvents can be used herein insofar as they are able to aiddissolution of the polycarbosilane and at the same time effectivelycontrol the viscosity of the resulting polymeric solution as a coatingsolution. Various facilitating measures such as stirring and/or heatingmay be used to aid in the dissolution. Suitable solvents includehydrocarbon solvents such as methylisobutylketone (MIBK), dibutyl ether,xylene, benzene, toluene, n-heptane, hexane, cyclohexane, octane,decane, or cyclic dimethylpolysiloxanes and the like. Typically, coatingthicknesses are between 0.1 to about 15 microns. As a dielectricinterlayer, the film thickness is generally less than 2 microns.

The polycarbosilane-modified poly(arylene ethers) of the presentinvention can also be used as interlayer dielectrics in an interconnectassociated with a single integrated circuit (“IC”) chip. An integratedcircuit chip would typically have on its surface plural layers of theinstant polycarbosilane-modified poly(arylene ether) dielectric andmultiple layers of metal conductors. It can also include regions of thepolycarbosilane-modified poly(arylene ether) dielectric between discretemetal conductors or regions of conductor in the same layer or level ofan integrated circuit.

In application of the instant polymers to ICs, a solution of one or moreof the poly (arylene ether)/polycarbosilane adhesion promotercompositions of the present invention is applied to a semiconductorwafer using conventional wet coating processes as, for example, spincoating (other well known coating techniques such as spraying can beemployed in specific cases). As an illustration, a cyclohexanonesolution of a polymer composition comprised of the compounds of formulaII and a small percentage of another polymer comprised of Formula I isspin-coated onto a substrate having electrically conductive componentsfabricated therein and the coated substrate is then subjected to thethermal film forming process of the instant invention. An exemplaryformulation of the instant composition is prepared by disolving thepoly(arylene ether)/polycarbosilane adhesive promoting composition incyclohexanone solvent under ambient conditions with strict adherence toa clean-handling protocol to prevent trace metal contamination in anyconventional apparatus having a non-metallic lining. The resultingsolution is comprised of from 1 to about 50 wt %, based on the totalweight of the solution of the poly (arylene ether)/polycarbosilanecomposition, and preferably from about 3 to 20 wt %, the remainder beingsolvent.

Application of the instant adhesion promoted poly (arylene ether)polymer compositions onto planar or topographical surfaces or substratescan be carried out by using any conventional apparatus, preferably aspin coater, because the poly (arylene ether)/polycarbosilanecompositions used herein have a controlled viscosity suitable for such acoater. Evaporation of the solvent by any suitable means, such as simpleair drying by exposure to an ambient environment or by heating on a hotplate to 250° C., can be employed in the coating application of thepresent low k dielectric polymer/polycarbosilane composition.

The instant poly (arylene ether)/polycarbosilane compositions can alsobe used as a dielectric substrate material in circuit boards or printedwiring boards. The circuit board made up of the subject poly (aryleneether)/polycarbosilane adhesion promoter compositions will have mountedon its surface patterns for various electrical conductor circuits. Thecircuit board may include, in addition to the instant poly (aryleneether)/polycarbosilane substate, various reinforcements, such as wovennon-conducting fibers or glass cloth. Such circuit boards may be singlesided, as well as double sided.

After application of the poly (arylene ether)/polycarbosilane adhesionpromoter compositional coating to an electronic topographical substrate,the coated structure is subjected to the process of the presentinvention wherein the coating is subjected to a bake and cure thermalprocess at increasing temperatures ranging from 50° C. up to 450° C. topolymerize the coating to its organosilicon-modified poly(arylene ether)form. The resulting dielectric layer has a low dielectric constant kdefined herein as being 3 or less. These organosilicon-modifiedpoly(arylene ether)polymer compositions physically demonstrate goodadhesion to flat or topographical semiconductor surfaces or substrates.

While not to be construed as limiting it is speculated that the thermalprocessing of the present poly (arylene ether)/polycarbosilanecomposition results in a crosslinked network of the poly(arylene ether)and adhesion promoting polycarbosilane portions of the originalcomposition. In essence, the instant thermal processing of the poly(arylene ether)/polycarbosilane composition causes the silane portionsof the polycarbosilane to convert to silylene/silyl radicals which thenreact with both the unsaturated structures of the poly(arylene ethers)and the substrate surfaces, thereby creating a chemically bondedadherent interface for the dominant poly(arylene ether) precursor, thesesilylene/silyl radicals being available throughout the composition toact as attachment sources to fasten and secure any interface surface ofcontact by chemical bonding therewith. As already indicated, thisdispersion of radicals throughout the composition accounts for thesuperb adhesion of the instant films to both underlying substratesurfaces as well as overlayered surface structures such as cap ormasking layers illustrated in FIG. 2.

Crucial to the materials discovered herein are the findings that thepolycarbosilanes of Formula I have a reactive hydrido substitutedsilicon in the backbone structure of the polycarbosilane. This featureof the polycarbosilane enables it to: (1) be reactive with the poly(arylene ether) portion of the coating composition and; (2) generate apolycarbosilane-modified poly (arylene ether) polymer which is durableunder hostile semiconductor processing steps.

Heat curing can be carried out at any temperature and time suitable forcompletion of the conversion of the poly(arylene ether)/polycarbosilanepromoter composition to an polyorganosilane-modified poly(arylene ether)polymer composition to generate a dielectric layer. However the curingtemperature should not be below 400° C. because a lower temperature isinsufficient to complete the completion of the reaction herein.Generally, it is preferred that curing is carried out at temperatures offrom 400° C. to about 450° C. Curing can be carried out in aconventional curing chamber such as an electric oven, hot plate, and thelike and is generally performed in an inert (non-oxidizing) atmosphere(nitrogen) in the curing chamber. Any non oxidizing or reducingatmospheres (eg. Argon, Hydrogen and Nitrogen processing gases) may beused in the practice of the present invention, if they are effective toconduct curing of the organosilicon-modified poly(arylene ether)composition to achieve the low k dielectric film herein.

In illustrative FIG. 1, a semiconductor structure 10 comprised of apolycarbosilane-modified poly(arylene ether) dielectric interlayer 12 isshown coated on semiconductor substrate 14. Note that the instantdielectric layer 12 has a flat planarized surface which masks thestepped profile of the patterned metal layer which has two types ofpatterned steps, i.e., a relatively wide step region 16A, such as anelectrode, and a relatively narrow step region 16B such as conductivewiring. After formation and patterning of a metal layer to achieve themetal pattern shown, the instant poly (arylene ether)/polycarbosilaneadhesion promoter composition layer is spin coated over the metal lines16A and 16B using the composition of respective formulas (II) and (I)above. Thereafter this film coating is then subjected to the thermalprocess described herein resulting in the flat dielectric interlayer 12surface demonstrating the planarization character of the instant low kdielectric polycarbosilane-modified poly(arylene ether) polymercomposition. Accordingly, the instant polycarbosilane-modifiedpoly(arylene ether) polymer composition and preparation thereof can beemployed to sequentially coat multiple patterned metal layers.

FIG. 2 illustrates one embodiment of a semiconductor wafer structureemploying the adhesion enhanced compositions of this invention. Thewafer 20 as shown includes a conductive substrate layer 22 which iscovered with an insulating layer 24 comprised of a low k dielectricpolycarbosilane modified poly (arylene ether) composition of the presentinvention. The low k dielectric layer 34 is covered or overlayed with asilicon dioxide mask or cap layer 28. As depicted, the structurefeatures a fully metallized via or trench comprised of copper (or copperalloy) 26 over a thin Ta or TaN barrier layer 29. This semiconductorstructure is obtained by spin, baking and curing apolycarbosilane/polyarylene ether composition onto the substrate 22 inthe manner outlined herein to form low k dielectric layer 24. Thedielectric coated substrate is then subjected to a chemical vapordeposition of silicon dioxide mask or cap layer onto the dielectriclayer. The resulting layered substrate is then subjected to a patterningprocess by deposition of photoresist, imaging, and washing byconventional lithographic means. The resulting pattern on the device isetched through the SiO₂ mask and organic dielectric layers, providing acontact hole or line for metallization. A thin Ta or TaN barrier layer29 is deposited in the contact hole or line and a layer of copper (orcopper alloy) is deposited on the barrier layer to form metallized plugor line 26. The resulting semiconductor device configuration isplanarized by chemical mechanical polishing techniques known in the artto form the structure of FIG. 2.

As indicated earlier, the subject polycarbosilane-modified poly(aryleneether) polymer composition coating may act as an interlayer and becovered by other coatings, such as other dielectric (SiO₂) coatings,SiO₂/modifying ceramic oxide layers, silicon containing coatings,silicon carbon containing coatings, silicon nitrogen containingcoatings, silicon nitrogen carbon containing coatings and/or diamondlike carbon coatings. Such multilayer coatings are taught in U.S. Pat.No. 4,973,526, which is incorporated herein by reference. And, as amplydemonstrated the polycarbosilane-modified poly(arylene ether)compositions prepared in the instant process can be readily formed asinterlined dielectric coatings or films between adjacent conductor pathson fabricated electronic or semiconductor substrates.

The following non-limiting Examples are provided so that one skilled inthe art may more readily understand the invention.

EXAMPLE 1

A 15% solution of a poly(arylene ether) comprised of a homopolymer of(a) fluorene bisphenol and (b) 4-fluoro-3′-(fluorobenzoyl)tolane in a1:1 monomer ratio, synthesized in earlier cited copending patentapplication Ser. No. 09/197,478, is prepared by dissolving 100 grams ofthe solid homopolymer in cyclohexanone under ambient conditions in aglasslined reactor. 10 grams of Polyallylhydridocarbosilane,[[Si(CH₂CHCH)HCH₂]_(0.1)[SiH₂CH₂]_(0.9)]_(n) (AHPCS) purchased fromStarfire Systems, Inc. was dissolved in 200 milliliters ofcyclohexanone. The solution is then added to the base homopolymeric poly(arylene ether)/solvent solution with stirring to effect completesolution of the poly(arylene ether)/polycarbosilane mixture. Theresulting solution is then filtered through a series of four Teflon®filtration cartridges and the polycarbosilane/poly(arylene ether)homopolymer solution is recovered. The filtration cartridges havedecreasing nominal pore sizes of 1.0, 0.5. 0.2, and 0.1 μm.

EXAMPLE 2

A 13% solution of a poly(arylene ether) comprised of a copolymer of: (a)fluorene bisphenol, (b) a bis(4-fluorophenyl)ethyne, and (c) 4,4′difluorobenzophenone in a 2:1:1 monomer ratio synthesized in copendingpatent application Ser. No. 09/197,478, is prepared by dissolving 80grams of the solid copolymer in cyclohexanone under ambient conditionsin a glasslined reactor. Eight (8) grams of allylhydridopolycarbosilane,[[Si(CH₂CHCH)HCH₂]_(0.1)[SiH₂CH₂]_(0.9)]_(n). (AHPCS) purchased fromStarfire Systems, Inc. was dissolved in 100 milliliters ofcyclohexanone. This polycarbosilane solution is then added to the basecopolymeric poly (arylene ether)/solvent solution with stirring toeffect complete solution of the poly (arylene ether)/polycarbosilanemixture. The resulting solution is then filtered through a series of thesame sized four Teflon® filtration cartridges of Example 1 and thepolycarbosilane/copolymeric poly (arylene ether) solution recovered.

EXAMPLE 3

A 15% solution of a poly(arylene ether) comprised of a homopolymer of(a) fluorene bisphenol and (b) bis(4-fluorophenyl) ethyne, synthesizedin copending patent application Ser. No. 09/197,478, is prepared bydissolving 100 grams of the solid copolymer in cyclohexanone underambient conditions in a glasslined reactor. Ten (10) grams ofPolyallylhydridocarbosilane,[[Si(CH₂CHCH)HCH₂]_(0.1)[SiH₂CH₂]_(0.9)]_(n) (AHPCS) purchased fromStarfire System, Inc. was dissolved in 200 milliliters of cyclohexanone.The solution is then added to the base poly(arylene ether)/solventsolution with stirring to effect complete solution of the poly(aryleneether)/polycarbosilane mixture. The resulting solution is then filteredthrough a series of the same sized four Teflon® filtration cartridges ofExample 1 and the polycarbosilane/homopolymeric poly (arylene ether)solution recovered.

EXAMPLE 4

A 20% solution of a poly(arylene ether) comprised of a homopolymer of(a) fluorene bisphenol and (b) 4,4′ difluorobenzophenone copolymer,synthesized in copending patent application Ser. No. 09/197,478, isprepared by dissolving 110 grams of the solid copolymer in cyclohexanoneunder ambient conditions in a glasslined reactor. 8 grams ofPoludihydridocarbosilane (HPCS), [SiH₂CH₂]_(n), purchased from StarfireSystems, Inc. was dissolved in 80 mls. of cyclohexanone. Thispolycarbosilane solution is then added to the dominant poly (aryleneether)/cyclohexanone solution with stirring to effect complete solutionof the poly(arylene ether)/polycarbosilane mixture. The resultingsolution is then filtered through a series of the same sized fourTeflon® filtration cartridges of Example 1 and thepolycarbosilane/poly(arylene ether) solution recovered.

EXAMPLE 5

This example demonstrates a process for the application of the instantadhesion promoter enhanced poly(arylene ethers) to silicon semiconductorwafers.

Approximately 3 mls. of the respective filtered solutions of Examples1-4 were separately processed onto the surfaces of four inch siliconwafers using a spin coater and hot plate oven track, for example aSilicon Valley Group, Inc. (SVG) Model No. 8828 coater and SVG Model No.8840 oven track. After the solution was dispensed, each wafer was spunat 500 rpm for 5 seconds, followed by a 5 second rest and a sixty secondspin at various speeds between 1000 and 5000 rpm. Each of the coatedwafers were baked at thermal plateaus of 150° C., 200° C., and 250° C.for about one minute at each temperature. Each wafer was then cured in anitrogen atmosphere in a furnace set initially at 400° C. for one hour,followed by a cool down to 100° C. The process generated apolycarbosilane modified poly (arylene ether) film coated waferemploying the organic coating materials from each of Examples 1-4.

EXAMPLE 6

The purpose of this Example is to demonstrate the preferredconcentrations of the polycarbosilane promoters of the present inventionfor maintaining the adhesion characteristics of the instantpolycarbosilane modified poly(arylene ether) wafer coatings prepared inthe same general manner as outlined in Examples 1-4 above. VariousCyclohexanone solutions of dihydridopolycarbosilane and Allied Signal'sFLARE™ and FLARE™ 2.0 are prepared, processed into films, and spun ontoTEOS and SiN coated wafers in a manner as described in Examples 1-5 andsubjected to solvent delamination and stud pull tests. FLARE™ is apoly(arylene ether) comprised of a homopolymer of (a) fluorene bisphenoland (b) 4-fluoro-3′-(4-fluorobenzoyl) tolane in a 1:1 monomer ratio (seeExample 1) and FLARE™ 2.0 is a copolymer of (a) fluorene bisphenol, (b)bis (4-fluorophenyl) ethyne, and (c) 4,4′ difluorobenzophenone copolymer(see Example 2) in a 2:1:1 monomer ratio. The results of these tests areoutlined in Table 1.

In the solvent delamination test, the tendency of the present organicfilms to delaminate is enhanced by exposure of the films to a hotamine-based solvent, ACT 690, available commercially from AshlandChemical Co. and generally employed as a cleaning solvent insemiconductor processing. The hot solvent enters the film either bydiffusion through the film or entry through an interface. It istheorized that any delamination is caused by the solvent effectively“outcompeting” the organic film for bonding sites on the oxide ornitride surfaces. In this test, the organic film is spun onto thedesired TEOS and SiN substrates and cured for 1 hour by conventionaltechniques well known in the art and illustrated in Example 4. The waferis cleaved to generate an approximate 2″ by 1″ sample which is markedwith a grid in one comer of the sample. The sample is exposed to ACT 690for 30 minutes at 70° C. in a small vial with agitation, rinsed withdeionized (DI) water, and allowed to air dry. Any film delaminationobserved in the solvent bath or rinse is noted and recorded as a failedsample.

A tape test is performed across the grid marking in the followingmanner: (1) a piece of adhesive tape, preferably Scotch brand#3m600-1/2X1296, is placed on the film and pressed down firmly to makegood contact; and (2) the tape is then pulled off rapidly and evenly atan angle of 180° to the film surface. The sample is considered to passif the film remains intact on the wafer, or to have failed if part orall of the film pulls up with the tape.

In a Stud Pull Test, epoxy-coated studs are attached to the surface of awafer containing the films of the present invention. A ceramic backingplate is applied to the back side of the wafer to prevent substratebending and undue stress concentration at the edges of the stud. Thestuds are then pulled in a direction normal to the wafer surface by atesting apparatus employing standard pull protocol steps. The stressapplied at the point of failure and the interface location are thenrecorded. A pull value of 9 kilo-pounds per square inch (kpsi) (1kpsi=1000 pounds per square inch) is considered satisfactorypolymer/interface adhesion for semiconductor wafers.

TABLE 1 Post ACT 690 Tape Test Results for Post ACT 690 Tape FLARE ™ 2.0Test Results for % Polycarbosilane/ polymer on oxide FLARE ™ polymerPoly(arylene ether) and nitride on oxide and nitride Post ACT Stud pullConcentration substrates. substrates. values. 0   Failed Failed  <1 kpsi0.4 Failed Failed 0.8 Passed Passed >11 kpsi 2.0 Passed Passed 4.0Passed Passed

The qualitative data of Table 1 for both tests demonstrates that apolycarbosilane in a concentration of about 0.5% by weight of thepoly(arylene ether) polymer is effective in promoting film adhesion toboth TEOS (oxide) and SiN coated semiconductor substrates. Therefore, apolycarbosilane promoter concentration between about 0.5 wt % and 20 wt% of the poly(arylene ether) base polymer is considered the effectiverange of polycarbosilane additive in the instant poly (aryleneether)/polycarbosilane-modified polymer compositions, with preferredconcentrations being from about 0.5 to 5 wt. %. As indicated, theseconcentration ranges of polycarbosilane adhesion promoter in thepolycarbo-silane-modified poly(arylene ether) polymer are effective withboth the TEOS and SiN coated substrates to maintain adhesion of theinstant polymer films to the TEOS or SiN layers.

The polycarbosilane adhesion promoter/poly (arylene ether) compositionsof the present invention provide unexpected adhesive properties as afilm coating material and particularly a polymer composition useful as areplacement for silica based-dielectric material in electronic surfaces.The poly (arylene ethers) and the polycarbosilane adhesion promoters arealso easily synthesized or readily accessible.

While foregoing is directed to the preferred embodiments of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. An adhesion promoter composition comprising atleast one compound having the formula:

wherein: R₁, R₇ and R₁₀ each independently represents a substituted orunsubstituted alkylene, cycloalkylene or arylene group; R₂, R₃, R₄, R₅,R₈ and R₉ each independently represents a hydrogen atom or organicgroup; R₆ represents an organosilicon, a silanyl, a siloxyl, or anorgano group; and x, y, z and w satisfy the conditions of[4≦x+y+z+w≦100,000] and y, z and w can collectively or independently bezero, with the proviso that when y>0, then z>0.
 2. A film coatingcomposition, comprising: the adhesion promoter compound of claim 1; anda low k dielectric polymer.
 3. The film coating composition of claim 2,wherein the low k dielectric polymer comprises an organic polymer. 4.The film coating composition of claim 2, wherein the low k dielectricpolymer comprises a phenylethynylated-aromatic monomer or oligomer. 5.The film coating composition of claim 2, wherein the adhesion promotercompound is present from about 0.5 to about 20 percent by weight.
 6. Adielectric polymer composition having an internal compositional additivecomprising the adhesion promoter compound of claim
 1. 7. The dielectricpolymer composition of claim 6, wherein the dielectric polymer comprisesan organic polymer.
 8. The dielectric polymer composition of claim 6,wherein the dielectric polymer comprises a phenylethynylated-aromaticmonomer or oligomer.
 9. A film comprising the dielectric polymercomposition of claim
 6. 10. The film of claim 9, wherein the film iscured.
 11. The film of claim 10, wherein the adhesion promoter compoundeffects in-situ adhesion capability.
 12. A spin-on compositioncomprising the dielectric polymer composition of claim
 6. 13. Thespin-on composition of claim 12, wherein the composition furthercomprises a solvent.
 14. The film of claim 10, wherein the film is curedby subjecting the film to radiation from a radiation source comprisingultraviolet radiation, electron beam radiation and combinations thereof.15. The spin-on composition of claim 12, wherein the spin-on compositionis cured.
 16. The spin-on composition of claim 13, wherein the spin-oncomposition is cured.
 17. The spin-on composition of claim 15, whereinthe spin-on composition is cured by subjecting the spin-on compositionto radiation from a radiation source comprising ultraviolet radiation,electron beam radiation and combinations thereof.
 18. The spin-oncomposition of claim 16, wherein the spin-on composition is cured bysubjecting the spin-on composition to radiation from a radiation sourcecomprising ultraviolet radiation, electron beam radiation andcombinations thereof.
 19. The film coating composition of claim 2,wherein the film coating composition is cured.
 20. The film coatingcomposition of claim 19, wherein the film coating composition is curedby subjecting the film coating composition to radiation from a radiationsource comprising ultraviolet radiation, electron beam radiation andcombinations thereof.